JPH1192121A - Method for purifying phosphorus oxychloride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain purified POCl3 by distilling impure POCl3 in the presence of a high b.p. nitrogen compd. selected from among substd. pyridines, substd. pyrimidines, open chain and cycloaliphatic amines, open chain and cyclic amidines, guanidines and arom. amines. SOLUTION: In a batch system, impure POCl3 is first charged, a high b.p. nitrogen compd. is then added by <10 wt.% and the POCl3 is distilled. In a continuous or semicontinuous system, the high b.p. nitrogen compd. is first introduced by 10-100 wt.% based on the amt. of POCl3 , impure POCl3 is then added and distilled and impure POCl3 is further added in accordance with the progress of distillation. Continuous operation is carried out until the nitrogen compd. as still residue leaks in the resultant distillate and the residue is incinerated. The high b.p. nitrogen compd. having >=140 deg.C b.p. is selected from among alkylpyridines, aryl group substd. pyridines, condensed ring substd. pyridines, open chain and cycloaliphatic amines, open chain and cyclic amidines, guanidines, arom. amines, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a phosphorous ester (ph
The present invention relates to a method of purifying impure phosphorus oxychloride (POCl ₃ ), which would result in a product having an increased color number in the manufacture of an osphorus ester. In particular, by-products in the production of chlorinated nitrogen heterocycles (co-products)
A method for purifying impure POCl ₃ formed as t) is described.

[0002]

BACKGROUND OF INVENTION Problems to be Solved] For example, by reaction of the corresponding poly hydroxypyrimidine and PCl ₅ or PCl ₃ + Cl _2, chlorinated N heterocycles such production of polychlorotrifluoroethylene pyrimidines, many Patent application,
For example, European Patent No. 697406 (EP697)
406), WO 96/23776, EP 7
No. 45593 (EP745593) or EP761653 (EP761653). In this reaction, in addition to the chlorinated heterocycle, POCl as a by-product in an amount equivalent to the total amount of chlorine atoms introduced
_{3 is} also obtained. The use of this POCl ₃ for further synthesis is urgently needed from economic and ecological point of view.

[0003] POCl ₃ is used in the chemical industry, inter alia, as an intermediate for the production of aliphatic or aromatic phosphates. For example, to be usable as auxiliaries in the plastics or photographic industries, these phosphates must not have a unique color. For example, depending on the particular method for the production of polychlorinated pyrimidines, the POCl ₃ obtained here is so impure that it cannot be used for the synthesis of phosphorus-containing esters that can be used without limitation. . For example, similar boiling impurities containing carbon, chlorine, oxygen or nitrogen may be present in POCl ₃ removed by distillation. These impurities lead to an increase in the number of colors in the phosphorous ester synthesis. The redistillation of impure POCl ₃ is an efficient column (column)
Even through s) does not lead to satisfactory removal of impurities. Therefore, there is a need for a method that can improve the quality of POCl _{3 to} the extent that it can be used without limitation in the production of phosphorus-containing esters.

[0004]

SUMMARY OF THE INVENTION A high boiling point selected from the group consisting of substituted pyridines and pyrimidines, open and cyclic aliphatic amines, open and cyclic amidines, guanidines and aromatic amines. A method of purifying POCl ₃ has been found which comprises distilling impure POCl ₃ in the presence of nitrogen compounds.

[0005] Purification relates in particular to POCl ₃ from the synthesis of chlorinated N-heterocycles.

The nitrogen compounds which can be used according to the invention are those which have a sufficiently high boiling point and do not appear as new impurities or only in traces in the POCl ₃ distillate in the distillation according to the invention. is there. These are nitrogen compounds according to the invention having a boiling point of> 140 ° C., preferably> 170 ° C., particularly preferably> 200 ° C. (all at normal pressure). For easy handling, their melting points should be at most 60 ° C, preferably at most 40 ° C.

Examples which may be mentioned are the alkyl pyridines or the polyalkylated pyridines, for example 4-methylpyridine, 4-tert-butylpyridines, dimethylpyridines, the various regioisomers of trialkylated pyridines ( pyridines substituted with an aryl group, such as 2,4,6-trimethylpyridine, for example, 2-, 3- or 4
-Position isomers of phenylpyridine, diphenylpyridines or triphenylpyridines, for example, 2,4,6-
Fused rins such as triphenylpyridine
gs) substituted pyridines, such as quinoline, isoquinoline, acridine. These named systems are derivatized with further substituents (d
rivatized). Examples which may be mentioned are quinaldine or p-hydroxyquinoline. Oligo- or polypyridine derivatives, for example 2,2'-
Bipyridyl, 3,3'-bipyridyl, 4,4'-bipyridyl, 2,4'-bipyridyl, 2,6-bis (2-pyridyl) -pyridine and the like can further be used according to the present invention. Other examples of pyridine derivatives according to the present invention are pyridines substituted by amino groups, such as 4-aminopyridine, 4-dimethylaminopyridine and the like. Pyridine, oligo- and polypyridine derivatives substituted by mixed alkyl, aryl, amino and by fused rings can also be used.

Examples of other high-boiling nitrogen compounds which can be used according to the invention are pyrimidines corresponding to the pyridines mentioned.

Other examples include open-chain and cycloaliphatic amines,
Open-chain and cyclic amidines or guanidines, such as trioctylamine, triisobutylamine, alkylpiperidines, diaza-bicyclo-nonane (DBN), diazabicyclo-undecane (DBU), tetramethylguanidine and similar with a suitable boiling point Nitrogen compound. Finally, aromatic amines such as aniline, N
-Methylaniline and the like are suitable.

According to the invention, it is possible to use individual nitrogen compounds or mixtures of a plurality thereof. Preferred nitrogen compounds are pyridine derivatives and open-chain or cyclic amidines or guanidines.

According to the invention, in a batch process, the addition of nitrogen compounds to impure POCl ₃ is less than 10% by weight;
Preferably it is less than 5% by weight, particularly preferably less than 1% by weight. However, it is also possible to use more than 10%, in which case, in continuous or semi-continuous form, the high-boiling nitrogen compounds are distilled off from the distillation still.
It is possible to use it many times as an illumination bottom or to recycle it.

The distillation according to the invention can be carried out at elevated, reduced or normal pressure, with normal pressure being preferred. The method can be performed batchwise or continuously.

The distillation according to the invention can be carried out in various ways. As an example, impure POCl ₃ can be introduced first. The nitrogen compound (s) according to the invention are then mixed in, after which the purified POCl
₃ is distilled off through a column. 140-2
When a nitrogen compound having a boiling point range of 00 ° C. is used, P
It is advantageous to use a column effective to avoid nitrogen compounds in the OCl ₃ distillate. At boiling points of nitrogen compounds above 200 ° C., lower efficiency separation columns are no longer sufficient. However, first the nitrogen compound is introduced and then the impure P
It is also possible to add OCl ₃ and distill it off from the mixture according to the invention. In this connection, it is advantageous to initially introduce, for example, more than 10% by weight, for example up to 50% by weight or even up to 100% by weight, based on the amount of relatively large amounts of nitrogen compounds, for example POCl _3. It is. If the POCl ₃ distilled off here is replaced intermittently or continuously by further impure POCl ₃ , the process can be carried out in large quantities so that the bottoms are such that impurities can escape into the distillate. Can be operated continuously until the impurities are contained. Exhausted (e
xhausted nitrogen compounds are professionally treated by incineration including, for example, flue gas treatment. Finally, the selected weight ratio of impure PO
The Cl ₃ and nitrogen compounds can be fed together or separately to a continuously operated distillation column, the purified distillate being withdrawn as the top product and the nitrogen compounds being withdrawn as the bottom product. The still product is recycled and supplied again as nitrogen, a small portion of the remaining product is removed, disposed of and replaced by fresh nitrogen. When supplying separately, nitrogen compounds are preferably supplied above the POCl _3.

[0014]

The following examples illustrate the method according to the invention without limiting it.

Example A Tricresyl phosphine from POCl ₃ for color number determination
Preparation of the phosphate (aromatic phosphate) A mixture of 200 g of m-cresol, 80 g of p-cresol and 50 g of phenol is treated with 0.1 g of MgO and, with stirring, with 153.5 g of POCl ₃ to be tested. After this, the mixture is heated to an internal temperature of 330-340 ° C. with stirring (HCl evolution) for 10 hours. It is then cooled slightly and distilled at 10 mbar. The product passes over in the top temperature range of 230-270 ° C. The main stream is washed twice with 100 ml of 0.1N NaOH at 60 ° C. and twice with 100 ml of water. The wet tricresyl phosphate phase is then
Dry at 100 ° C. Determine the color number of the dried aromatic phosphate.

Example B Trichloropropyl from POCl ₃ for Color Number Determination
Preparation of the phosphate (aliphatic phosphate) 153.5 g of POCl ₃ to be tested are initially introduced and treated with 0.8 g of TiCl ₄ at room temperature.
Thereafter, 232 ml of propylene oxide are added dropwise over 1 hour. The internal temperature is kept at ８０80 ° C. by external cooling.
The mixture is then stirred at 80 ° C. for 1 hour and finally a water jet vacuum is applied to remove propylene oxide residues. After this, the mixture was washed with 0.1N HCl1
Once at 80 ° C. with 100 ml, once with 100 ml of water, 0.1 ml
Wash once with N NaOH and once with 100 ml of water.
Finally, the product is dried by applying a water jet vacuum at ９０90-100 ° C. The color number of the aliphatic phosphate under drying is determined.

Example 1 POCl ₃ distillate from the production of dichloropyrimidines having a color number of 180 Hazen according to Example A) and a color number of 380 according to Example B) 153 g were treated with 1.0% by weight of quinoline and refluxed for 1 hour. Then 144 g of a colorless distillate was distilled off at normal pressure (top temperature 106 ° C.) through a 10 cm long column. The number of colors according to Example B) is 40
Hazen and the color number according to Example A) was 20 Hazen.

Example 2 145 g of a colorless POCl ₃ distillate are obtained by repeating Example 1 using 1.0% by weight of quinaldine instead of quinoline, which has a color number according to Example B). He gave 35 Hazen.

Example ₃ 1000 g of POCl _{3 of} Example 1 was added to collidine (coll).
treated with 10 g and normal pressure (top temperature about 1
(05 ° C.) through a 1 m long packed column. 955 g of a colorless distillate was obtained. The color number determination according to Example A) gives 15 Hazen and the color number according to Example B) is 2
He gave 5 Hazen.

Examples 4 to 6 153 g of POCl ₃ distillate from the preparation of dichloropyrimidines having a color number of 430 Hazen according to Example B) are treated with 4-phenylpyridine, 4-dimethylaminopyridine or 2,2. '-Dipyridyl, in each case 1.0
Treated in wt%. After distillation as in Example 1, 35, 30, and 45 Hazen were obtained in the color number determination according to Example B).

EXAMPLE 7 As Example 1, 500 g of POCl ₃ distillate from the production of trichloropyrimidines having a color number of 280 Hazen according to Example B), using 1.0% by weight of quinoline Was purified. After distillation, the color number according to Example B) was 20 Hazen.

The main features and aspects of the present invention are as follows.

1. Impure POCl in the presence of a high boiling nitrogen compound selected from the group consisting of substituted pyridines and pyrimidines, open and cyclic aliphatic amines, open and cyclic amidines, guanidines and aromatic amines _Three
A process for purifying POCl ₃ comprising distilling POCl ₃ .

2. The process of claim 1 wherein POCl ₃ obtained as a by-product in the production of the chlorinated N-heterocycle is used.

3. The method of claim 1 wherein the nitrogen compound has a boiling point of> 140 ° C. at normal pressure.

4. 2. The method according to the above 1, wherein the nitrogen compound used is a pyridine derivative.

5. 2. The method according to the above 1, wherein the nitrogen compound used is an open-chain or cyclic amidine or guanidine.

6. In a batch process, the P to be purified
The process of claim 1 wherein less than 10% by weight of the nitrogen compound is used, based on the amount of OCl ₃ .

7. In a continuous process, using an amount 10 to 100% by weight of nitrogen compound, based on the of POCl _3, and the nitrogen compound, for further POCl ₃ purified and or recycled used until exhaustion 2. The method according to 1 above.

Claims (1)

[Claims] 1. The presence of a high-boiling nitrogen compound selected from the group consisting of substituted pyridines and pyrimidines, open-chain and cyclic aliphatic amines, open-chain and cyclic amidines, guanidines and aromatic amines. Impure POCl ₃ below
A process for purifying POCl ₃ comprising distilling POCl ₃ .